Flaps 2 origin 737?

[stilton]

No Flaps one gate on the B727.



The detents are at 2, 5, 15, 25, 30 and 40.



Many Airlines blocked off the 40 selection as 30 was more than adequate for most runways and the sink rate with flaps 40 could get away from you very quickly if you weren't careful.

[Johnny Tightlips]

I use F2 a quite a bit on the -800. If ATC have you level 15 miles out and ask for 180KTS it's a very useful setting. If I'm on the glide I just use F5 or F10 if needed.

[A37575]

Flap 2 in the 737-200 was used extensively at high altitude airports where Flap 1 was a problem with its higher V speeds. I think it was South America where Flap 2 was mainly used. Depending on runway lengths etc, the weights used for Flap 1 and 2 were normally max structual up to around 2000 ft airport altitude.

One advantage of Flap 2 if the choice was available, was a Human Factor aspect, in that the next flap (which was Flap 1) could be selected normally at V2 +15, which left the leading edge devices still extended.

This minimised the danger of someone inadvertently (carelessly?) when conducting a Flap 1 take off, retracting the flaps to up at V2 +15 instead of first accelerating to 190 knots (53 tonnes and below). On quite a few occasions I observed pilots calling for Flaps up at V2 +15 on a Flap 1 take off.

[Old Smokey]

I've no experience on the B737-200, only the B737-300. The low Flap settings available are not necessarily applicable to Takeoff considerations, but may have other useful functions.

On the B777 for example, Flaps 1 has no use for Takeoff (standing by for a blast for someone who uses it), Flaps 5 is the lowest used. Where it IS useful, particularly as the later and heavier B777s have high manoeuvering speeds, is for Holding, where the clean holding speed exceeds the limit for the pattern in use, and when a dispensation against the 250 Kt limit below 10000 ft cannot be obtained, Flaps 1 becomes a necessity (Definately NOT recommended in iceing conditions).

Regards,

Old Smokey

[aterpster]

stilton:

Many Airlines blocked off the 40 selection as 30 was more than adequate for most runways and the sink rate with flaps 40 could get away from you very quickly if you weren't careful.

As demonstrated by a UAL 727-100 at Salt Lake City circa 1965 or thereabouts.

[Shiny side down]

B737-800. Flaps2 while vectoring

Dragging up an old thread
I've been trying to find some information on this, and was happy to see that some other folk have used F2.

I once or twice called for it many moons ago when fuel was becoming an issue, and the big gulf between F1 and F5 speeds suggested that F5 was a bit excessive when keeping a much higher speed, such as 180kt during arrivals into places like London.

On one occasion, I was informed that if it isn't trained, it cannot be used.

On the NG, if you select F2, it bugs a speed of around 180kt. So the machine isnt surprised to see it, Which means Boeing must have something built in to use it. It has a position in the gauge, a detent in the quadrant, and a bug on the tape.
I know of at least one operator that has now determined it to be not available for use. No explanation given or available.

Is there any other detailed info or explanation of this otherwise superfluous flap position?

[captplaystation]

My 2nd favourite setting due to the aforementioned 180kt ability, my fav being Flap 10 (but not on the SFP aircraft where it is now useless) which is "best friend" on intermediate approaches when ATC just get it that little bit tight & getting those leading edges out does the trick nicely without resorting to gear/speedbrakes.

[Shiny side down]

Dammit, I was hoping that something would prove me wrong or ill-informed and that ops manuals authors were in possession of better info, rather than just a pen with which to dictate against that which they don't understand.

[BOAC]

someone once whimsically said that it came from the B17 flap selector and Boeing had a few hundred left on the shelf.gate. Certainly after -200 I have never seen it 'approved' by thems-wot-knows'.

[Shiny side down]

There is sufficient information in the various Boeing manuals discussing the action of the leading edge devices when using flaps 1,2 & 5, but not one bit of data or advice saying not to use it, except in the company manuals with which Boeing has no direct input.

[caber]

I've wondered this myself. My airline specifically prohibits flaps 2, with many a bulletin to reinforce it.

We also use flaps 1 for takeoff when needed in both the 800 and 900. Honestly, the tail clearance isn't as big an issue as the v1 and vR speeds. Rejecting a takeoff at speeds close to flaps 1 v1 would be an interesting exercise in braking.

[Denti]

Try it with an improved speed schedule at F1, V1s in higher 160s are quite interesting, especially if you have to chuck along at derate 2 plus 60° ATM, waiting over a minute until you can rotate.

[30W]

on th NG F2 works great when ATC want 180kt as part of approach sequencing! F1 doesn't normally allow 180kt to be flown, F2 does have the speed tape bug move lower to allow 180kt and provides less drag/more efficiency than taking F5

[boofhead]

The B737-100 used F2 for takeoff, it gave a similar performance as the B737-200 using F5. I used it on the B737-150 a lot (a B737 basic with the advanced wing). I was told it was gated because that was the go around flap setting for the B727 with one engine out and it was easier to set it correctly with the gate than without. For convenience they fitted the same flap mechanism in the B737 when it was first made, as they used the same fuselage jigs etc. It could have been the go around flap setting for the basic B737-100 as well and was left there even after the bigger engines and better performance of the later models because it was easier to to do that than re-engineer the flap mechanism?
It went out of favour when the airlines started using Boeing-generated takeoff charts, for which a great deal of money had to change hands. Having just one or two options for flap settings on takeoff would save a lot of money in chart costs and the bean counters would not know the difference in fuel consumption and cost. However a tail strike due to not setting the correct bugs (thinking you were using the regular F5 and the associated speeds) would offset many years of costs for the fuel savings due to a more optimum flap setting.